#include <stdio.h>
using namespace std;

const int dim = 100005;
int N, M, K, A[dim], B[dim];

void cit ()
{
	scanf ("%d%d%d",&N, &M, &K);
	for (int i = 1, x, y; i <= M; i++)
	{
		scanf ("%d%d", &A[i], &B[i]);
	}
}

int main ()
{
	freopen ("stergeri.in", "r", stdin);
	freopen ("stergeri.out", "w", stdout);
	
	cit ();
	for (int i = M; i >= 1; i--)
	{
		if (A[i] <= K)
			K += B[i] - A[i] + 1;
	}
	printf ("%d\n", K);
	
	return 0;
}